Magnetic targeting system for facilitating navigation

ABSTRACT

The present invention describes a magnetic targeting system suitable for guiding a biocompatible device to a target area within the body (in vivo) and method of using the same. The system includes a targeting member having a steering material and is attached to the biocompatible device. The system also includes at least one anchoring member constructed and arranged for the inclusion of a magnetic material effective for influencing the traversal of the steering material, in vivo. The magnetic material is configured and sized so as to positionable external of the anchoring member, in vivo. The magnetically influenced anchoring member interacts with the targeting member such that the biocompatible device is positionable relative to the target area. An extender and connector have threads indexed to a securing set screw to facilitate positioning and affixation of the biocompatible material

PRIORITY CLAIM

This application is a continuation in part of application Ser. No.11/462,592 filed on Aug. 4, 2006 entitled Magnetic Targeting System andMethod of Using The Same, which is hereby expressly incorporated byreference.

FIELD OF THE INVENTION

The invention generally relates to surgical implants; particularly to asystem and method for stabilization of adjacent bony structures; mostparticularly to a system to help navigate an interconnecting meansbetween multiple bony stabilization devices.

BACKGROUND OF THE INVENTION

It is widely held that healing and/or structural correction is greatlyfacilitated when a bone is stabilized in the proper position. Variousdevices for stabilization of bone are well known and routinely practicedin the medical arts. For example, an abnormal spine can be stabilizedusing a substantially rigid or semi-rigid interconnecting means (rod orplate) and fastening means (screws, clamps, hooks, claws, anchors, orbolts). Multiple fasteners are placed into the spinal pedicle of eachvertebra and linked by at least one interconnecting means. One of themore difficult aspects is the surgical insertion of the interconnectingmeans along a fixed path of delivery longitudinally along the vertebraeand through each of the multiple fastening means between multiplevertebrae. Once in place, this system substantially immobilizes thespine and promotes bony fusion (arthrodesis).

Traditionally, the surgical techniques for stabilization of bonerequired large incisions (upwards of 6 cm in length) and a considerableamount of muscle be cut and stripped away (retracted) from the bone foran “open” visualization of the bone and access thereto for the placementof the fasteners and instrument implantation. Although this so-called“open” surgical technique has successfully treated non-unions,instability, injuries and disease of the spine, it is not withoutdisadvantages. Given the invasive nature of this technique, a lengthyhealing time and considerable post-operative pain for the patient iscommon.

In response to aforementioned drawbacks, the surgical arts havedeveloped minimally invasive systems and procedures intended to replacethe more traditional open surgeries. Obviously, a less extensive systemand procedure will eliminate the need to perform much of the cutting andstripping of muscle, resulting in reduced recovery time and lesspost-operative pain. As a result, percutaneous procedures have beendeveloped which insert instruments and perform operations through smallskin incisions, usually between 1.5 and 5 cm in length, thereby reducingsoft tissue damage. However, smaller skin incisions and smaller surgicalfields require more novel and innovative approaches to perform thesecomplicated surgeries.

One such example of a minimally invasive system is the SEXTANT Spinalsystem by Medtronic (Memphis, Tenn.). This device is comprised of twobasic components, screw extenders, and the rod inserter, which resultsin an instrument that looks like a sextant used in naval navigation. Thedevice is an insertion tool that allows fasteners and interconnectingmeans to be applied to the spine in a minimally invasive manner. Thescrew extenders are long shafts used to deliver and attach screws to thevertebrae through small skin incisions. During surgery, these extendersprotrude outside the body, allowing the surgeon to arrange and jointheir ends so that the rod inserter may be attached. The rod inserter isan arc-shaped arm that swings along a fixed axis and pushes aninterconnecting rod though the skin and muscle and into the heads of theimplanted fasteners (pedicle screws).

While the aforementioned technique is adequate when the fastening meansare well aligned, it fails to deliver the rod when one of the screws ismisaligned. Moreover, the interconnecting rod must be pushed by thesurgeon along a fixed arch and cannot be directed around neuralstructures or bony obstructions. One consequence of forcibly pushing therod through the fastening means is the possibility of collision betweenthe rod and a bony obstruction causing a piece of bone to break offresulting in possible neurological damage. Another common problem is theinterconnecting rod becoming disengaged from the rod inserter. Wheneither of these incidents happens, additional surgery is often requiredto remove the bone fragment and rod from the wound. This may result inthe surgeon abandoning the minimally invasive approach and reverting toa traditional approach. Current spinal implant systems do not allow thecontour of the rod to match the normal curvature of the surroundinganatomy and such systems are not customizable to meet the individualanatomical variables that each patient presents.

In order to help avoid damaging sensitive anatomy and expedite implantassembly, various image-based navigation systems have been employedwhich utilize patient images obtained prior to or during the medicalprocedure to guide a surgeon during the surgery. Recent advances inimaging technology have produced detailed two and three dimensionalimages using optically guided, fluoroscopic guided, and electromagneticfield based systems. These image-based systems have also been used incombination with the previously described “open” surgeries. Onesignificant problem with most image-based systems is that the radiationgenerated is transmitted to the patient and surgical staff, which mayresult in physiological damage over time. Also, the cost and portabilityof this equipment continue to be an issue. In addition, these systemsoften require the surgeon undergo extensive training to operatecorrectly.

Accordingly, a need exists in the surgical arts for a system andminimally invasive procedure capable of providing optimal mechanicalsupport and bony fusion, while reducing the likelihood of bone damageand neural functioning when compared to the currently availableinterconnecting elements. It is also desirable to provide a surgicalprocedure that can be performed in conjunction with, but does notrequire, an image-based tracking system.

PRIOR ART

Although there are numerous patents directed to systems and methods forinsertion of a stabilizing implant at a selected area of an anatomy, theprior art nevertheless fails to teach a targeting system for theinsertion of an implant using minimally invasive techniques having adecreased risk of causing damage to neural structures or bonyobstructions using minimal, if any, radiation exposure to the patientand/or surgeon.

For example, U.S. Publication No. 2005/0085714 to Foley et al.,discloses a method and apparatus for percutaneous and/or minimallyinvasive implantation of a construct (e.g., spinal implant). Theconstruct may be implanted using a navigation system for planning andexecution of a procedure. A plurality of portions of the construct maybe interconnected using locations and paths determined and navigatedwith the navigation system. The navigation system utilizes optical orelectromagnetic localization to determine the precise location of aselected implant construct or instrument. An optical localizer can bepositioned relative to an extender attached to a screw. Alternatively, acoil may be positioned in an electromagnetic (EM) field such that theposition of the coil may be determined by sensing the induced voltage. Acomputer is used to form a plan prior to implantation of the constructand thereafter track the various portions of the construct duringinsertion. The plan and the tracking of the surgery are displayed on amonitor to provide guidance to the surgeon.

U.S. Publication No. 2005/0277934 to Vardiman, discloses a minimallyinvasive spinal fixation system used for spinal arthrodesis (bonyfusion) or motion preservation. The system comprises a plurality ofpedicle screws, including a first screw placed into a first vertebralbody, and a second screw placed into a second vertebral body, aconnector for attaching to the first and second screws and, a removableguide for percutaneously attaching the connector to the first and secondscrews. According to one embodiment, detectional spheres are positionedon the head of screw extenders and on the handle of the rod insertiontool. A comparator calculates the relative position of the insertiontool handle with respect to the screw extenders and provides a visualdisplay for the surgeon.

U.S. Pat. No. 6,236,875 to Bucholz, discloses surgical navigationsystems including reference and localization frames. The systemgenerates an image representing the position of one or more bodyelements during the procedure using magnetic resonance imaging(hereinafter, MRI) or computed tomography (hereinafter, CT) scan imagestaken prior to the surgery. The body elements and their relativeposition are identified during the procedure. The position of the knownbody elements can then be manipulated using a computer to the relativeposition of the patient during the surgery. The manipulated data canthen be utilized to guide the surgeon for implantation.

U.S. Pat. No. 6,226,548 to Foley et al., discloses an apparatus andprocedures for percutaneous placement of surgical implants andinstruments such as, for example, screws, rods, wires and plates intovarious body parts using image guided surgery. The invention includes anapparatus for use with a surgical navigation system, an attaching devicerigidly connected to a body part, such as the spinous process of avertebra, with an identification superstructure rigidly but removablyconnected to the attaching device. This identification superstructure,for example, is a reference arc and fiducial array which accomplishesthe function of identifying the location of the superstructure, and,therefore, the body part to which it is fixed, during imaging by CT scanor MRI, and later during medical procedures. The system utilizesemitters such as light emitting diodes (hereinafter, LEDs), passivereflective spheres, acoustics, magnetics, electromagnetics, radiologic,or micro-pulsed radars for indicating the location of a body part towhich the emitter is attached.

U.S. Pat. No. 7,011,660 to Sherman et al., discloses a braceinstallation instrument and method for the stabilization of bonystructures. The installation instrument is sextant-type tool with anchorextensions coupled to the anchors. The instrument is movable withrespect to the anchors to position a brace in a position proximate tothe anchors. The brace can be indexed for insertion at a predeterminedorientation with respect to the installation instrument.

All of the aforementioned prior art disclose a system which utilize animplant insertion means to forcibly push the surgical implant orinstruments to the target area in vivo. This increases the possibilityof pathway divergence and/or damage to neural and vascular structures.What has been heretofore lacking in the prior art is a simple andeconomical system and procedure for the accurate and precise placementof surgical implants and/or instruments at a target area while providinga decreased risk to neural and vascular structures. Moreover, none ofthe aforementioned references provide audible and/or tactile feedback tothe surgeon that indicates the target area has been reached.

SUMMARY OF THE INVENTION

The instant invention is related to a magnetic targeting system suitablefor guiding a biocompatible device, (implant, surgical instrument) to atarget area within the body (in vivo), be it a tumor or implantationpoint for a fastening means. The system includes a targeting member thatincludes a steering material. The targeting member is attached at oneend to the biocompatible device. The system also includes at least oneanchoring member constructed and arranged to secure to a target area invivo at one end and the other end constructed and arranged for inclusionof a magnetic material effective for influencing the traversal of thesteering material in vivo. The magnetically influenced anchoring memberinteracts with the steering material of the targeting member such thatthe connected biocompatible device is positionable relative to thetarget area.

It therefore an objective of the instant invention to provide a systemthat minimizes soft tissue damage and provides less post-operative pain.

It is a further objective of the instant invention to provide atargeting system that provides real time targeting by providing feedbackas to the position of the biocompatible device.

Yet another objective of the present invention is to disclose a feedbacksystem that utilizes audio and/or tactile feedback to indicate to thesurgeon when the target area is reached.

Another objective of the present invention is to provide a magnetictargeting system that can penetrate tissue without being distorted orcausing physiologic damage, unlike x-rays.

Still a further objective of the invention is to teach a targetingsystem which allows for shorter surgery, decreased x-ray exposure, andfewer complications for the patient.

Yet another objective of the instant invention is to provide a targetingsystem that is simple to operate to reduce the training the surgeon mustundergo for operation of peripheral systems.

These and other objectives and advantages of this invention will becomeapparent from the following description taken in conjunction with anyaccompanying drawings wherein are set forth, by way of illustration andexample, certain embodiments of this invention. Any drawings containedherein constitute a part of this specification and include exemplaryembodiments illustrate various objects and features thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a partial side view of a portion of a patient's spinewhich includes magnetic targeting system according to a preferredembodiment of the invention;

FIG. 2 is the magnetic targeting system as shown in FIG. 1, illustratingthe targeting member with attached tethering means threaded through ananchor member;

FIG. 3 is the magnetic targeting system shown in FIG. 1, illustratingthe targeting member being removed from the interior of the patientthrough the last extender;

FIG. 4 is the magnetic targeting system as shown in FIG. 1, illustratingthe insertion of the biocompatible device between adjacent vertebrae;

FIG. 5 is a partial cross-sectional view of a portion of the extenderremovably attached to the connector portion of the multi-axial screw inaccordance with one embodiment;

FIG. 6 is an upper perspective view of a multi-axial screw that can beused in system of the present invention;

FIGS. 7 a thru 7 e illustrate various embodiments of the targetingmember used in the instant invention;

FIG. 8 is a partial side view of portion of the spine of a patient whichincludes the magnetic targeting system according to another embodimentillustrating the insertion of the targeting member in vivo without theuse of extenders; and

FIG. 9 illustrates a partial side view of a portion of a patient's spinewhich includes magnetic targeting system according to another embodimentof the invention using a permanent magnet.

FIG. 10 is a perspective view of the magnetic device and magneticcatcher with the magnetic catcher protruding out of the extender andconnector member.

FIG. 11 is a perspective view of the magnetic device and magneticcatcher with the magnetic catcher positioned within the extender andconnector member.

FIG. 12 is a perspective view of the magnetic device and magneticcatcher in a position in an upper portion of the extender.

FIG. 13 is a perspective view of the magnetic catcher in contact with atarget member of the first fastener.

FIG. 14 is a sectional view of an extender and connector member eachhaving internal threads that are indexed to one another so that that setscrew may be threaded downwardly through the extender and the connectorto secure the biocompatible material in place with respect to thefastener.

FIGS. 15 A through 15 O illustrate the various steps necessary forinstallation of the surgical implants where the connecting memberbetween the fastening members is pulled into place.

FIGS. 16A through 16L illustrate the various steps the various stepsnecessary for installation of the surgical implants where the connectingmember between the fastening members is pushed into place.

FIGS. 17A and 17 B are perspective views of an alternative embodiment ofa magnetic catcher.

FIGS. 18A, 18B and 18C are side views of another alternative embodimentof a magnetic catcher.

FIG. 18 D is a front view of the catcher of shown in 18A-18C.

FIG. 18E is a perspective view of the catcher shown in FIGS. 18A-Dremoved from the extender.

FIG. 19A is a perspective side view of a device used to determine theshape of the rod prior to insertion into the patient.

FIG. 19B is a top view of the installed device shown in FIG. 19A.

FIG. 19C is a top view of the device shown in FIG. 19A.

FIGS. 19D and 19E are opposite side views of the device shown in FIG.19A.

DETAILED DESCRIPTION OF THE INVENTION

Detailed embodiments of the instant invention are disclosed herein,however, it is to be understood that the disclosed embodiments aremerely exemplary of the invention, which may be embodied in variousforms. Therefore, specific functional and structural details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representation basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure.

Referring now to FIGS. 1-9 which illustrate the magnetic targetingsystem 10 of the present invention suitable for facilitating navigationto a target area, wherein like elements are numbered consistentlythroughout. FIG. 1 shows a plurality of anchoring members 14 (alsoreferred to as fastening means). The anchoring members are depicted hereas multi-axial pedicle screws, each removably attached to an extender 12a, 12 b, 12 c. These screws have a proximal end 16 and a distal end 18.The proximal end includes head portion 24 with a tool opening 26configured to receive a driving tool (not shown). The distal endincludes a threaded shank designed to secure to a selected target arealocated inside the body of a patient (in vivo), shown here asconsecutive spinal vertebrae V1, V2, V3. Although the target area isexemplified here as vertebrae in a partial spinal column the target areamay be located anywhere in vivo.

The screw shown here is a multi-axial screw where the proximal end ofthe screw may include a connector 28 rotatably connected to the headportion 24 of the screw. That is, the connector is capable of 360 degreerotation relative to the threaded shank 27 of the screw along the axis Lof the shank and angular motion defined by the angle α (FIG. 5). Oneexample of a suitable multi-axial screw is described in U.S. Pat. No.5,797,911, herein incorporated by reference. Although a multi-axis isexemplified herein, it is contemplated that a fixed axis screw may beused. Fixed-axis screws do not include a rotatable connector 28. Othermeans for anchoring are also contemplated herein, some of which include,clamps, hooks, claws, bolts, or the like. Moreover, the shank of theanchor member may or may be not be cannulated, as is known in the art.

As shown in FIGS. 5 and 6, the connector portion of the screw isconstructed and arranged to form a passageway 30 designed to removablyreceive implants of various sizes. The connector portion includes anopening 43 constructed and arranged to receive a set screw 38. As shownin FIG. 6, the head portion includes threaded interior sidewalls 46designed to mate with external threads 38 formed on the set screw. Thus,as the set screw is threadably lowered along the connector portion ofthe screw the passageway 30 in the connector is narrowed. The passagewayis narrowed until the exterior surfaces of the biocompatible device 44(shown here as interconnecting rod, see FIGS. 1-4) are sandwichedbetween the upper portion of the screw head 24 and the set screw. Thisacts to reliably secure the biocompatible device onto the screw. As withthe head of the screw, there should be a tool opening 40 configured toreceive a driving tool (not shown) inserted within the interior portion74 of the extenders. The driving tool is well known in the surgical artsand is used to rotatably secure the set screw to the desired positionwithin the interior of the connector.

As discussed above, the distal end 34 of each of the hollow extenders 12a, 12 b, 12 c are removably attached to the screws by any appropriatemeans known in the art. For example, the extender may include adepressible member (not shown) located at the proximal end 33 of theextender that is operatively connected to an internal clamping memberlocated that the distal thereof. The clamping member is capable ofengaging and disengaging the connector portion of the screw. One exampleof a suitable extender which could be used in the present invention isdisclosed in U.S. Pat. No. 7,011,660, herein incorporated by reference.The extender may also be able to rotate the connector of a multi-axialscrew relative to the shank to facilitate the threading of theinterconnecting rod there through.

The extenders should be made of a substantially rigid biocompatiblematerial and have a length dimension (along its longitudinal axis 50)that allows the proximal end 33 to protrude a distance outside of thepercutaneous exposure 22 created through the outer skin S of thepatient. According to a preferred embodiment, at least the firstextender should have a “c-shape”, as seen along an axis transverse itslongitudinal axis, thereby defining a slot 63 that extends along itslongitudinal axis 50 and into the patient when attached to the screw.The slot should be sized to allow the targeting member to exit, so thatit is able to be delivered percutaneously, as shown in FIG. 1. Theinterior dimension 76 of the extenders should be such that they arecapable of receiving the appropriate driving tool (not shown) used toengage the screws and set screws. In addition, the interior dimension ofthe extenders should be able to accept a removable magnetic device 60for magnetically influencing the anchor members 14, as described furtherbelow.

Referring again to FIGS. 1-4, a targeting member is shown attached tobiocompatible device 44 by a tethering means 42. The targeting memberhas a first end 52 and a second end 54. The first end is designed topenetrate the tissue and is shaped to enlarge the opening while creatinga pathway through the tissues as the targeting member is advanced invivo. At least the first end of the targeting member is composed of asteering material capable of being magnetically influenced, as describedhereafter.

As shown in non-limiting embodiments of FIGS. 7 a-e, the targetingmember 20 may be made from a flexible, semi-rigid, or rigid material,each includes the steering material 84 located on the first end. FIG. 7a illustrates an embodiment of a semi-rigid targeting member in the formof rod-like member with steering material 84 disposed on its first end52. The first portion 78 of the rod is made of a flexible materialcapable of safely colliding with bony or neural obstructions withoutcausing damage. FIG. 7 b illustrates another flexible rod formed of aplurality of rigid consecutive segments 80 through which the tetheringmeans 42 extends to the first end (not shown). When the surgeon pullsthe tethering member at the second end taunt, the segments are forcedtogether and little movement is permitted between the segments. In theembodiment of FIG. 7 c, the entire targeting member is composed of orcoated with a second biocompatible steering material 86. FIG. 7 dillustrates another embodiment wherein the targeting member includes aball joint 88 attached to the tethering means. As with the embodiment ofFIG. 7 b, the tension in the tethering member controls the amount ofpivot at the ball joint. Thus, when tension is released the rod comesflexible and the first end of the targeting member pivots on the ball.Alternatively, when the tension is reapplied to the tethering means, therod is solid again. This way the surgeon is able to safely guide thetargeting member around neural and bony obstructions as it moves throughthe body. Lastly, FIG. 7 e depicts a rigid rod-like member formed fromsolid biocompatible material 90.

The tethering means 42 may be made of any flexible or semi-flexiblebiocompatible material capable of allowing the device to navigate aroundneural and bony obstructions without damaging them. Examples of suitabletethering means may be in the form of a cable, cord or ligament.Moreover, the tethering means may be formed of a cannulated or solidmember. As discussed above, the first end 92 of the tethering means isattached to the second end 54 of the targeting member by any means ofattachment known in the art. Similarly, the second end 94 of thetethering means is attached to the biocompatible device 44 by any meansof removable connection known in the art. For example, the biocompatibledevice and tethering means could include corresponding threads that thesurgeon can rotate to disconnect the tethering means from thebiocompatible device.

According to a preferred embodiment, the biocompatible device is shownas an implantable interconnecting rod. The rod may be rigid, semi-rigidor flexible. Rigid rods are usually preferred for providing thenecessary stability during the healing process and arthrodesis, however,flexible rods have been found to provide for arthrodesis while allowingsome movement between bony structures that have been interconnected topreserve some motion. Moreover, like the tethering means thebiocompatible device may also be solid or cannulated.

Although the interconnecting rod is shown in FIGS. 1-4 asinterconnecting two pedicle screws, the surgeon could use anyappropriately sized rod having a length dimension capable ofinterconnecting three or more fastening means co-linearly implantedalong multiple vertebrae. It is also within in the purview of theinvention that any sized rod having various widths or diameters could beused so long as it is capable of stabilizing the bony structures forbony fusion. Although a rod-like member is exemplified herein, othersuch biocompatible devices known to one skilled in the art are alsocontemplated, for example, plates, clamps, etc.

FIG. 4 illustrates a hollow or cannulated flexible biocompatible devicein fluid communication with a cannulated tethering means. According tothis embodiment, once the rod has been properly inserted into thedesired location, the surgeon can use an insertion means 96 (syringe orthe like) to supply a biocompatible hardening material (e.g., cement,carbon, bone matrix) through the tethering means and into the interiorof the hollow rod. Although not required, the biocompatible device mightalso be made permeable and used to deliver constituents supplied by theinsertion means to the target area (e.g., bone growth/fusion material,medication, curing material, etc.).

As shown in FIGS. 1-4, each of the proximal ends of the extenders 12 a-cprotrude outside of the patient's skin through percutaneous incisions 22so that the surgeon is able to insert instrumentation through theextender's interior portion to access the screw secured to the targetarea (vertebra). The extenders also enable the surgeon to insert themagnetic device or wand 60 into the selected extender to a positionproximate the corresponding anchor 14. The magnetic device includes aproximal 64 and a distal end 66. Magnetic material 62 is attached at thedistal end of the device and the proximal end may include a grip 100(not required) for the surgeon to hold the magnetic device. The wandshould be sized to extend the length of the extender.

The “magnetic material” 62 as used herein refers to either a permanentmagnet (as shown in FIG. 9) or an electromagnet (shown in FIGS. 1-4)which generates a magnetic field capable of influencing the steeringmaterial in the targeting member in vivo. As is known in the art, anelectromagnet is a magnet in which the magnetic field is produced by aflow of electrical current. One example of a suitable permanent magnetis a Neodymium Iron Boron (NdFeB) magnet since it is powerful and hasbeen approved by the U.S. Food and Drug Administration (FDA) forinternal use. Another example is the use of a recently developedbiocompatible non-metallic magnet, or plastic magnet, made from thepolymer PANiCNQ which is combination of emeraldine-base polyanailine(PANi) and tetracyanquinodimethane (TCNQ).

The “steering” material in the target member, as used herein, refers toany material capable of being influenced by the magnetic material 62.For example, the steering material may include any magneticallyattractive material or alloy, (e.g. steel, iron, etc). The steeringmaterial may be the same or different than that used for magneticmaterial 62 so long as it is capable of being influenced, e.g.,attracted or repelled. Moreover, either or both the magnetic materialand the steering material may be coated with any suitable biocompatibleelement, such as plastic. The type, shape, and size of the magneticmaterial and steering material should be suitable for internal use inpatients and provide the optimal magnetic field. Magnetic fields areused herein for navigating in vivo since these fields can penetratehuman tissue and bone without being distorted similar to x-rays, butwithout the danger of radiation and physiologic damage.

According to a preferred embodiment shown in FIGS. 1-4, the magneticmaterial employs an electromagnet having controls located in the handleor grip 100. At a minimum, the controls should include buttons andassociated circuitry that will allow the surgeon to turn theelectromagnet on 102 and off 104. Preferably, the controls also includebuttons and circuitry capable of increasing 106 or decreasing 108 thestrength of the magnetic field generated by the electromagnet and/orswitch between polarity (north and south poles). As is known, thepolarity of a magnet allows it to attract or repel magnetic materialwithin its magnetic field. The controls can also include a display 110used to indicate the strength of the magnetic field being applied.

The method of using the magnetic targeting system 10 of the presentinvention is described in accordance with the embodiment depicted inFIGS. 1-4. First, the anchoring member 14 (shown here as the multi-axialpedicle screw) is inserted into the desired target area (shown here asvertebra), as is known in the surgical art. The screw may be removablyattached to the distal end of the extender before or after attachment ofthe screw to the selected vertebrae. Once attached, the surgeon insertsthe targeting member into the proximal end of the extender whichprotrudes outside of the percutaneous exposure 22. The magnetic deviceis inserted into the next vertebra V2 which includes the anchoringmember (extender and screw), shown here as 12 b. The magnetic material62 is disposed proximate the target area via wand 60. According to thisexample, the magnetic material is placed inside the connector portion ofthe screw, this may be done prior to, during, or after the targetingmember is inserted into the extender. If an electromagnet is used, thesurgeon will switch on the electrical current to begin generating anattractive magnetic field when in the proper position in vivo. If apermanent magnetic is used for the magnetic material 62, the surgeonsimply places it inside the connector portion of the screw, see FIG. 9.

As a result of the attractive magnetic field, the steering material inthe targeting member is pulled through the extender slot 63. Thestrength of the magnetic field generated by the magnetic material shouldbe capable of pulling the targeting member (including attached tetheringmean) toward the magnetic member such that the pointed first endpenetrates the tissue and creates a pathway through the tissues as thetargeting member is advanced toward the magnetic material. The use ofthe magnetic field to guide the targeting member, as compared toforcibly pushing the targeting member, as disclosed in the prior art,reduces the probability of damaging neural structures or breaking bonyobstructions encountered along its path.

Once the targeting member has reached the magnetic material 62positioned inside the connector portion of the screw, the surgeonremoves it from the anchoring member and places it into the nextanchoring member (extender and screw), shown here as 12 c attached tovertebra V3. The aforementioned procedure is then repeated insideanchoring member 12 c. If an electromagnet is used, the electricityalong the magnetic member is turned on and the strength of the magneticfield generated pulls the targeting member through the passageway 30 ofthe screw secured to V2 and toward the magnetic member located insidethe screw secured to V3, see FIG. 2. If a permanent magnet is used, thesurgeon simply places the distal end inside the connector portion of theanchor.

As described before, the pointed first end of the target memberpenetrates the tissue and creates a pathway through the tissues as itmoves toward the magnetic material. This technique of threading throughthe screw does not require the surgeon to try to align multiple pediclescrews along the fixed path of the rod. Moreover, the continuousmagnetic attraction of the targeting member toward the pedicle screwreduces the possibility that the target member will be diverted bystructures in the anatomical topography that may cause it to penetrateunintended areas. In addition, the present invention allows the surgeonto avoid a given anchor member. In such a circumstance the surgeon caninsert the magnetic material into that extender connected to the anchormember that is to be avoided. The magnetic material maybe either apermanent magnet or electromagnet having the same polarity as that ofthe targeting member. This will repel the steering material of thetarget member from that target area.

Once the final vertebra is reached, the magnetic member is used to pullthe targeting member through the slot in the upper opening 43 of thepedicle screw and along the interior length of the extender until itreaches the proximal end protruding out of the incision. The surgeon canthen grasp the targeting member and attached tethering means, see FIG.3. The tethering means located outside the patient is then used by thesurgeon to gently pull the attached biocompatible member (rod) along thepath formed through the tissue by the targeting member and through theconnector portion of the pedicle(s) until the biocompatible memberreaches the last vertebra, as shown in FIG. 4.

If the tethering means and interconnecting rod are hollow, the user candisconnect the targeting member and releasably attach an injection means96 thereto. The injecting means can be used into supply any suitable anyflowable, biocompatible material inside the rod. One example of asuitable biocompatible material includes at least one a hardeningmaterial that will cause the rod to become rigid.

Otherwise, the rod might be filled prior to the introduction of ahardening material. For example, the rod might contain ferroelectricmaterial that allows the rod to remain flexible during insertion processuntil exposed to an electric current. This is particularly suitable ifused in conjunction with the electromagnet embodiment previouslydescribed. Once the flexible rod is positioned at the final desiredlocation (secured to pedicle screws), the rod may then be exposed toelectric current in the electromagnet by inserting the magnetic meansinto the extenders. The electric current causes the ferroelectricmaterial to harden to make a substantially rigid rod. Thus, the contourof the rod corresponds to the natural curvature of the surroundinganatomy.

As discussed above, the connector portion of the screw is constructedand arranged to receive a set screw 32 therein. The set screw isinserted into each of the extenders and threadably attached by thedriving tool (not shown) positioned in the extender and inserted in toolopening in the screw. The interconnecting rod 44 is sandwiched betweenthe upper portion of the head and the set screw. This acts to secure therod onto the screws. The extenders are then removed from the connectorportion of the screw and the exposures closed.

Referring to an alternative embodiment shown in FIG. 8, the targetingsystem of the present invention does not require the use of an extensionmember for insertion of the targeting member in vivo. The anchoringmember may be implanted and the exposure closed with no external accessthereto. The proximal end of the implanted anchoring member may includeeither a permanent magnet or a remotely controlled electromagnet, as isknown in the art. Thus, the targeting member 20 may be directly insertedand fed into the body through an incision created by the surgeon. Aswith the previous embodiments, the magnetic portion of the anchoringmember is capable of attracting or repelling the targeting member placedinside the patient.

Any of the aforementioned embodiments of the system and techniques ofthe present invention can employ any type of known imaging system todetermine and locate placement of any of the aforementioned structuresin vivo. For example, insertion of the anchor member into the bonystructure can be pre-planned by CT scan, x-ray, or the imaging meansknown in the art.

The present system may also include a feedback system having at leastone detection element 120 (two are shown in FIG. 1) disposed outside andproximate the patient to determine the position of the targeting memberand/or biocompatible member in real-time. According to one, albeitnon-limiting embodiment, the detection element is an audio receiver orpickup capable of audibly detecting when the targeting member andmagnetic means connect or “click” together. This way, the surgeon canimagelessly determine that the targeting member has reached themagnetized portion of the anchoring member. This may be used inconjunction with a tactile sensation produced when the targeting memberand magnetic means connect. This tactile sensation of the two elementsmeeting will be felt by the person holding the tethering means.

FIG. 10 shows a magnetic device or wand 160 with a turnable magneticcatcher 162 located at the distal end of the wand 160. The magnetic wand160 and magnetic catcher are sized to fit with the internal cavity 114of extender 112. The magnetic catcher 162 is constructed from any one ofthe magnetic materials noted above. It includes a first cylindricalportion 164 that is positioned coincident with the longitudinal axis ofthe wand 162. The diameter of the first cylindrical portion 164 ofmagnetic catcher 162 is larger than the diameter of the wand 160 but isless than the diameter of the internal 114 cavity of extender 112.Magnetic catcher includes a second cylindrical portion 166 which issmaller in diameter than the first cylindrical portion. Secondcylindrical portion 166 is generally “L” shaped and includes a verticalsection that transitions into a horizontal section through a ninetydegree turn. As shown in FIG. 10, the second cylindrical portion ofturnable magnetic catcher 162 can be moved to position that extendsoutwardly of inner cavity 114 through passageway connector 130 ofconnector 128 and passageway 132 in extender 112 and into the body. Themagnetic catcher 162 is then in a preferred position to attract andalign the targeting member 20 with passageways 132 and 130.

As shown in FIG. 11 the first and second portions of magnetic catcher162 are sized such that the magnetic device or wand 160 and magneticcatcher 162 may be inserted down to the bottom of extender 112 where thesecond cylindrical portion 166 of magnetic catcher 162 is aligned withpassageways 130 and 132. Likewise, as shown in FIG. 12 the wand 160 andmagnetic catcher 162 can be removed by pulling them up within the innercavity 114 of extender 112. The diameter of the first cylindricalportion 164 and geometry and size of the second cylindrical portion 166being such that the magnetic catcher 162 can be easily inserted andremoved from extender 112. FIG. 13 show the relationship between magnetcatcher 162 and the targeting member 20 when properly aligned.Conformation of positive engagement by repeated tactile “snap” or“click” between the magnetic catcher and the target indicates a properalignment of the rod 144 with passageways 130 and 132.

As shown in FIG. 14, the connector member 128 is constructed andarranged to form a passageway 130 designed to removably receive implantsof various sizes. The connector 128 includes an opening 143 constructedand arranged to receive a set screw 138. The opening 143 includesthreaded interior sidewalls 146 designed to mate with external threads139 formed on the set screw 138. The extender 112 includes an innercavity 114 that includes threads 116. The extender 112 is juxtaposed andmechanically engaged with the connector 128. The internal threads 116 ofthe extender 122 are indexed to the threads 146 in the connector 128.Thus, the set screw 138 is threadably lowered long the extender tubeuntil it reaches the threads 146 formed within opening 143 located inthe connector member 128. Since the threads 116 and 146 are indexed toone another the set screw 138 can continue to be threadably lowered intothe connector 128. The provision of threads within the extender that areindexed to the threads of the connector is particularly useful when morethan two screws are being connected with a rod or other biocompatiblematerial. It has been found that when more than two screws are connectedthat the biocompatible material, such as a rod, tends to ride upward inchamber 143 of the third and subsequent connector 128. It is thereforean advantage to begin the threaded engagement of set screw 138 prior toreaching the upper end of connector 128. As the set screw is lowered thepassageway 130 is narrowed until the exterior surfaces of thebiocompatible device 144 (shown here as an interconnecting rod, seeFIGS. 1-4) are sandwiched between the upper portion of the screw head124 and the set screw 138. As with the head of the screw 114, there is atool opening 140 configured to receive a driving tool. The tool iscapable of driving the set screw 138 through the extender 112 and intothe opening 143 to the desired position within the connector member 128.

FIGS. 15A through 15 O illustrate the various steps necessary forinstallation of the surgical implants where the connecting memberbetween the fastening members is pulled into place. FIG. 15A shows afreehand inserter 170 that is introduced into a caudal or cephladincision. The first fastening member, screw 114A, is approached underfluro, where the surgeon will feel for positive resistance. As thetarget 176, which is carried on the leading end of the freehand inserter170, approaches the magnetic catcher 162 the surgeon will feel forconformation of positive engagement by repeated tactile “snap” or“click”, as shown in FIG. 15B. With the target 176 in alignment withconnector passageway 130 and extender passageway 132 the catcher magnet162 and wand 160 are moved upwards within the extender 112A, asillustrated in FIG. 15C. FIG. 15D depicts the freehand guide 170 movingforward towards the second fastener 114B with the catcher magnet 162removed from the first extender tube 112A and placed in the secondextender tube 112B. FIGS. 15E, F and G illustrate the process for thesecond fastener 114B. The process is the same as it was for the firstfastener except much easier because of the close proximity between thefirst and second fastener. The freehand inserter 170 then advances thetip 176 towards the magnet catcher 162 positioned adjacent the thirdfastener 114C, as shown in FIG. 15H. The knob 172 on freehand inserter170 is then loosened which releases tether means 174 that is attached tothe magnetic tip 176. The magnetic tip 176 then follows the magneticcatcher as it is withdrawn from the third and last extender tube 112C asshown in FIGS. 15I and 15J. As shown in FIG. 15K, the magnetic tip 176follows the magnetic catcher out of extender 112C and the freehand guideis removed. At this point the tether means enters the initial incisionand all three screw connectors, 128A, 128B and 128C, and exits out thelast extender 112C, as shown in FIGS. 15L, 15M and 15N. A soft or solidrod can be pulled into place by positioning the rod with the freehandinserter 170 and pulling the tether means 174 through all three screwconnectors 128A, 128B and 128C. The rod is released from the wire 174using a break away connection 168 (see FIGS. 15 K and 15 O).

FIGS. 16A through 16L illustrate the various steps the various stepsnecessary for installation of the surgical implants where the connectingmember between the fastening members is pushed into place. FIG. 16Ashows an arrangement which uses a cannulated rod 180 which is assembledas part of the freehand guide 170 utilizing tether means 174, targetmember 176, and the tether means securing knob 172 on freehand guide170. In this arrangement the cannulated solid rod 180 carries thetargeting member 176 at its leading end and the cannulated rod is inturn positioned on the leading end of the freehand inserter 170. Thefirst fastening member, screw 114A, is approached under fluro, where thesurgeon will feel for positive resistance. As the target 176, which iscarried on the leading end of the cannulated rod 180, approaches themagnetic catcher 162 the surgeon will feel for conformation of positiveengagement by repeated tactile “snap” or “click”, as shown in FIGS. 16B,16C, 16D and 16E. With the target 176 in alignment with connectorpassageway 130 and extender passageway 132 the catcher magnet 162 andwand 160 are moved upwards within the extender 112A. FIG. 16F depictsthe freehand guide 170, cannulated solid rod 180 and magnetic tip 176pushed forward towards the second fastener 114B with the catcher magnet162 removed from the first extender tube 112A and placed in the secondextender tube 112B. FIGS. 16F, and 16G illustrate the process for thesecond fastener 114B. The process is the same as it was for the firstfastener except much easier because of the close proximity between thefirst and second fastener. The freehand inserter 170 then advances thecannulated rod 180 and the tip 176 towards the magnet catcher 162positioned adjacent the third fastener 114C, as shown in FIG. 16H. Theknob 172 on freehand inserter 170 is then loosened which releases tethermeans 174 that is attached to the magnetic tip 176. The magnetic tip 176then follows the magnetic catcher as it is withdrawn from the third andlast extender and the freehand guide is removed, as shown in FIG. 16I.The freehand guide 170 then pushes the cannulated rod into position onthe third fastener 128C and the magnetic target is released from thetether means 174 by a breakaway connector. The tether means 174 is thenremoved from the body. The installed cannulated rod 180 is shown in anassembled position in FIGS. 16J, 16K and 16L.

FIGS. 17A and 17B show an alternate embodiment to the magnetic device orwand 160 with a turnable magnetic catcher 162 located at the distal endof the wand 160, as shown in FIG. 10. In this embodiment the wand 260includes a hand holding grip 264 and a trigger like component 266pivotally attached thereto. Hand grip member 264 includes an elongatedrod like member 266. An additional rod like member 268 is positionedadjacent elongated rod member 266 and is hingedly connected to trigger266, via pivots 276 and 274 at one end, and hingedly connected tomagnetic catcher 262, via pivot 272 at the opposite end. Magneticcatcher 262 is also pivotally connected to elongated rod member at pivot270. Cantilevered flat springs 280 and 282 are positioned to bias thehand grip 264 and trigger 266 away from one another absent a forceexerted by the operator's hand. In operation, the operator's fingerswill grip trigger member 266 and pivotally move in towards the hand grip264. When springs 280 and 282 abut the trigger and the hand grip theywill act against the force exerted by the operator's fingers. Thepivotal motion of trigger 266 relative to hand grip 264 will result inthe relative axial displacement of rod like member 266 with respect toadditional rod like member 268. The relative displacement will result inthe pivotal movement of magnetic catcher 262, as shown in FIG. 17B, viathe displacement of pivot 270 with respect to pivot 272. The magneticwand 260 and magnetic catcher 262 are sized to fit with the internalcavity 114 of extender 112. The magnetic catcher 262 is constructed fromany one of the magnetic materials noted above.

FIGS. 18A and 18E show another alternate embodiment to the magneticdevice or wand 160 with a turnable magnetic catcher 162 located at thedistal end of the wand 160, as shown in FIG. 10. In this embodiment thewand 360 includes a hand held rod 368 and a magnetic catcher 362. Wand360 includes an upper cylindrical housing 372 and a push button actuator366. Depression of push button actuator 366 causes pivotal motion ofmagnetic catcher 362 push that it may swing to a position external tocavity 114 to a point external of extender 112.

FIGS. 19A through 19E illustrate a device used to determine thecurvature of rod 180 prior to insertion into the patient. The deviceprovides a way to transfer the location of the extender passageways andassociated pedicle screws to a position external of the body. Thisvisualization permits the surgeon to provide the best configuration forrod 180 prior to insertion into the body. FIG. 19A shows a perspectiveside view of extenders 112A through 112D and the device 400 as it wouldbe employed during a surgical procedure. The device 400 includes a plate402 which includes a track 404 which extends along the length of theplate 402. Slideably mounted within track 402 are mounting blocks 406.The number of mounting blocks 406 used corresponds to the number ofextender tubes 112 and associated pedicle screws. While four blocks 406have been shown it should be understood that as few as two blocks andmore than four blocks may be used. Each mounting block 406 carries apair of support rods. Each pair of support rods 406 in turn areconnected to an extender tube support block 410. Each extender tubesupport block 410 includes an aperture 412 sized to receive an extendertube 112. In use, each extender tube 112 is placed within a respectivesupport block 410. The support block and mounting block associated witheach extender tube is free to move along the track 404 within plate 402such that tubes are properly aligned. Once each of the tubes are sopositioned, a locking screw 420 is inserted in plate 402, through track404 and into each mounting plate 406. When the extender tubes 112A-112D,as shown in FIG. 19A, are properly positioned and locked into place byscrews 420 the surgeon can then proceed to shape the rod 180 in a mannerpresented by the upper surface of the extender tubes 112 A-D as shown inFIG. 19A. The preforming of the rod 180 prior to insertion into thepatient allows the surgeon to more easily thread the rod 180 through theextender passageways 132 located in extender tubes 112A-D that has beenimplanted within the patient and not visible to the surgeon.

Although the invention is described with reference to stabilization andfusion of adjacent spinal vertebrae, it is hereby contemplated thatdevices and methods disclosed herein could be used in all types ofjoints (ankle, interdigital, etc) found in the human or animal body.Although a rod-like member is exemplified herein, other suchbiocompatible devices known to one skilled in the art are alsocontemplated, for example, plates, clamps, etc.

All patents and publications mentioned in this specification areindicative of the levels of those skilled in the art to which theinvention pertains. All patents and publications are herein incorporatedby reference to the same extent as if each individual publication wasspecifically and individually indicated to be incorporated by reference.

It is to be understood that while a certain form of the invention isillustrated, it is not to be limited to the specific form or arrangementherein described and shown. It will be apparent to those skilled in theart that various changes may be made without departing from the scope ofthe invention and the invention is not to be considered limited to whatis shown and described in the specification and any drawings/figuresincluded herein.

One skilled in the art will readily appreciate that the presentinvention is well adapted to carry out the objectives and obtain theends and advantages mentioned, as well as those inherent therein. Theembodiments, methods, procedures and techniques described herein arepresently representative of the preferred embodiments, are intended tobe exemplary and are not intended as limitations on the scope. Changestherein and other uses will occur to those skilled in the art which areencompassed within the spirit of the invention and are defined by thescope of the appended claims. Although the invention has been describedin connection with specific preferred embodiments, it should beunderstood that the invention as claimed should not be unduly limited tosuch specific embodiments. Indeed, various modifications of thedescribed modes for carrying out the invention which are obvious tothose skilled in the art are intended to be within the scope of thefollowing claims.

1. A magnetic targeting system suitable for facilitating navigation to atarget area located in vivo, said system comprising: a targeting memberhaving a first end and a second end, said second end constructed andarranged for attachment to a biocompatible device and at least saidfirst end includes a steering material influenced by a magnetic field;and at least one anchoring member having a proximal end and a distalend, said distal end constructed and arranged to secure to a target arealocated in vivo, wherein said proximal end is constructed and arrangedfor inclusion of a magnetic material effective for influencing thetraversal of said steering material in vivo; and a extender having afirst open end and second open end and a cavity there between, the firstopen end of said extender being removably attached to said proximal endof said at least one anchoring member, said extender including apassageway, adjacent the first open end, between said cavity and anexternal surface of said extender, and, the second open end of saidextender protruding a distance outside of a percutaneous exposurecreated the outer skin of a patient; said magnetic material is sized andshaped to enter the extender at the second open end and move within saidcavity to a position adjacent the first open end of the extender and tomove through said passageway such that at least a portion of saidmagnetic material extends to a location external of said extender,whereby, the magnetically influenced proximal end of said anchoringmember interacts with said first end of said targeting member such thatsaid connected biocompatible device is positionable relative to saidtarget area.
 2. The magnetic targeting system of claim 1, wherein saidat least one anchoring members includes a plurality of anchoring memberseach capable of independently influencing said target member byinclusion of said magnetic material.
 3. The magnetic targeting system ofclaim 1, wherein said system includes a real-time feedback mechanism toverify location in vivo of said biocompatible device.
 4. The magnetictargeting system of claim 3, wherein said real-time feedback mechanismincludes tactile feedback to verify location in vivo of saidbiocompatible device.
 5. The magnetic targeting system of claim 1,wherein said magnetic material is a permanent magnet.
 6. The magnetictargeting system of claim 1, wherein said magnetic material is mounted adistal end of a wand, the magnetic material is in the form of a magneticcatcher, the magnetic wand and magnetic catcher are sized to fit withinthe passageway of said extender, the magnetic catcher can be turnedwithin the extender upon rotation of said rod and moved to position thatextends outwardly of said passageway and into the patient, whereby saidcatcher is then in a preferred position to attract and align thetargeting member.
 7. The magnetic targeting system of claim 1, whereinsaid magnetic material is mounted on a wand that includes a hand holdinggrip and a trigger like component pivotally attached thereto, said handholding grip member includes an first elongated rod like member, anadditional elongated rod like member is positioned adjacent said firstelongated rod member and is pivotally connected to said trigger likecomponent and is also pivotally connected to said magnetic materialthrough a pivot at an opposite end, said magnetic material is alsopivotally connected to said additional elongated rod, whereby pivotalmotion of trigger like component relative to said hand grip causesrelative axial displacement of said first rod like member with respectto said additional rod like member, and, said relative displacement willresult in the pivotal movement of said magnetic material.
 8. Themagnetic targeting system of claim 1 wherein said magnetic material ispivotally attached to a hand held rod at one end and is mounted in acylindrical housing at the opposite end, said housing includes a pushbutton actuator, whereby depression of push button actuator causespivotal motion of said magnetic material such that it may swing to aposition external of said extender.
 9. The magnetic targeting system ofclaim 1 wherein said biocompatible device is an implant or surgicalinstrument.
 10. The magnetic targeting system of claim 1 wherein saidbiocompatible device is formed from a material selected from the groupconsisting of rigid, semi-rigid, or flexible material.
 11. The magnetictargeting system of claim 2, wherein said anchor member is a fastenerfor attaching to a bony structure and said biocompatible device isconfigured to connect a plurality of anchor members.
 12. The magnetictargeting system of claim 1, wherein said targeting member ispositionable and mounted on a leading end of a free hand inserter, saidtargeting member is held in position adjacent said free hand inserter bya tether which is releasably secured to said free hand inserter.
 13. Themagnetic targeting system of claim 1, wherein said targeting member topositionable and mounted on a leading end of said biocompatible devicewhich in turn is mounted on the leading end of a free hand inserter,said targeting member is held in place by a tether which passes throughsaid biocompatible device and is releasably secured to said free handinserter.
 14. The magnetic targeting system of claim 12, wherein thebiocompatible material is released from the tether using a break awayconnection.
 15. The magnetic targeting system of claim 10, wherein thebiocompatible material is released from the tether using a break awayconnection.
 16. A magnetic targeting system suitable for facilitatingnavigation to a target area located in vi vo, said system comprising: atargeting member having a first end and a second end, said second endconstructed and arranged for attachment to a biocompatible device and atleast said first end includes a steering material influenced by amagnetic field; said biocompatible device is a cannulated rod; and atleast one anchoring member having a proximal end and a distal end, saiddistal end constructed and arranged to secure to a target area locatedin vivo, wherein said proximal end is constructed and arranged forinclusion of a magnetic material effective for influencing the traversalof said steering material in vivo; whereby, the magnetically influencedproximal end of said anchoring member interacts with said first end ofsaid targeting member such that said connected biocompatible device ispositionable relative to said target area.
 17. The magnetic targetingsystem of claim 16, further including a plate and block assembly adaptedto receive a plurality of extenders in a fixed position such that thelocation of the extending passageways are projected to location externalof the patient whereby the surgeon can then proceed to shape thecannulated rod in a manner presented by an upper surface of the extendertubes which allows the surgeon to more easily pass the cannulated rodthrough extender passageways located in said extender tubes.
 18. Amagnetic targeting system suitable for facilitating navigation to atarget area located in vivo, said system comprising: a targeting memberhaving a first end and a second end, said second end constructed andarranged for attachment to a biocompatible device and at least saidfirst end includes a steering material influenced by a magnetic field;and at least one anchoring member having a proximal end and a distalend, said distal end constructed and arranged to secure to a target arealocated in vivo, wherein said proximal end is constructed and arrangedfor inclusion of a magnetic material effective for influencing thetraversal of said steering material in vivo; an extender having a firstopen end and second open end and a cavity there between, the first openend of said extender being removably attached to said proximal end ofsaid at least one anchoring member, said cavity having threads extendingfrom said first open end to said second open end, said extenderincluding a passageway, adjacent the first open end, between said cavityand an external surface of said extender, and, the second open end ofsaid extender protruding a distance outside of a percutaneous exposurecreated the outer skin of a patient; whereby, the magneticallyinfluenced proximal end of said anchoring member interacts with saidfirst end of said targeting member such that said connectedbiocompatible device is positionable relative to said target area. 19.The magnetic targeting system of claim 18, wherein said anchoring memberincludes a connector member, said connector member includes a threadedportion that is indexed to the threads within said cavity, said cavitythreads and said connector threads being in juxtaposed relationship. 20.The magnetic targeting system of claim 19, further including a threadedset screw, said threaded set screw having threads that are indexed tothe threads within said cavity and on the threaded portion of theconnector member, said set screw threadably engages the threads of theinner cavity and is threaded down said inner cavity of said extenderfrom the second open end towards the first open end until it reaches thethreads on the threaded portion on the connector member the threadswithin the cavity and the threads on the connector member are indexed toone another such that the set screw can continue to be threadablylowered into the connector member.
 21. The magnetic targeting system ofclaim 20, wherein the biocompatible device is fastened to said connectormember by said set screw.
 22. A method for facilitating navigation to atarget area in vivo, said steps comprising: providing a targeting memberhaving a first end and a second end, said second end attached to abiocompatible device, wherein said first end includes a steeringmaterial influenced by a magnetic field; attaching to a target area invivo at least one anchoring member having a proximal end and a distalend, wherein said anchoring member is attached to said target area atits distal end; and introducing a magnetic material into said proximalend of said anchoring member and moving at least a portion of saidmaterial to a position outside of the anchoring member therebyinfluencing the traversal of said steering material, and positioningsaid biocompatible device relative to said target area.
 23. The methodas set forth in claim 22, wherein said at least one anchoring membersincludes a plurality of anchoring members each capable of independentlyinfluencing said target member by inclusion of said magnetic material.24. The method as set forth in claim 22, wherein said system includes areal-time feedback mechanism to verify location in vivo of saidbiocompatible device.
 25. The method as set forth in claim 24, whereinsaid real-time feedback mechanism includes tactile feedback to verifylocation in vivo of said biocompatible device.
 26. The method as setforth in claim 22, wherein said magnetic material is a permanent magnet.27. The method as set forth in claim 22 wherein said biocompatibledevice is an implant or surgical instrument.
 28. The method as set forthin claim 22 wherein said biocompatible device is formed from a materialselected from the group consisting of rigid, semi-rigid, or flexiblematerial.
 29. The method as set forth in claim 23, wherein said anchormember is a fastener for attaching to a bony structure and saidbiocompatible device is configured to connect a plurality of anchormembers.
 30. The method as set forth in claim 22, wherein said targetingmember is formed from a material selected from the group consisting ofrigid, semi-rigid, or flexible.